Peter Wijkens

The unusual solid state structures of the pentasubstituted bis( cyclopentadienyl) zinc compounds bis( pentamethylcyclopentadienyl) zinc and bis( tetramethylphenylcyclopentadienyl) zinc

Abstract The replacement of all hydrogen atoms of Zn(C 5 H 5 ) 2 by methyl groups causes a major change in the solid state structure. Whereas Zn(C 5 H 5 ) 2 is polymeric in the solid state, an X-ray diffraction study of Zn(C 5 Me 5 ) 2 has shown it to be a monomer, with one η 5 - and one η 1 -bonded ring. The crystals are monoclinic, space group P 2 1 / n with unit cell a 8.70(4), b 7.88(5), c 14.64(8) A, β 102.1(2)°, Z = 2. The structure is disordered. The crystal structure of Zn(C 5 Me 4 Ph) 2 has been studied in more detail. The compound crystallizes in the monoclinic space group P 2 1 / a , with unit cell a 8.086(1), b 17.640(2), c 8.823(1) A, β 93.70(2)°, Z = 2. Anisotropic full-matrix least-squares refinement with 1693 observed reflections and 158 parameters converged at R F = 0.0621. This compound is also monomeric. The zinc atom is disordered between two equivalent sites. In each site it is η 1 -bonded to one ring and η 5 to the other.

Coordination of a Ru(II)-complex to a tetrafunctional P-ligand: a model for Ru-P carbosilane dendrimers.

Organophosphine-functionalised carbosilane (CS) dendrimers (5, 6) can be synthesised in high yield. Furthermore, new kinds of metallodendrimers (7, 8) are obtained by coordination of a Ru(II) complex, containing the tridentate triamine ligand: 2,6-bis[(dimethylamino)methyl]pyridine, to these P-functionalised CS-dendrimers.

Insertion of norbornene into aryl–palladium(II) bonds: mechanistic aspects of the subsequent C–H activation

The insertion of norbornene into the Pd–C bond of the cationic phenylpalladium(II) complex [PdPh(pmdien)]OTf (2, pmdien =N,N,N′,N′,N″-pentamethyldiethylenetriamine, OTf = trifluoromethanesulfonate) yields a 1 : 1 enantiomeric mixture of an ortho 2-exo-norbornyl-substituted phenylpalladium(II) compound via selective, intramolecular C–H activation of the phenyl ring.

Unexpected formation of aryl-cyanides during the oxidative decomposition of aryl-cyanocuprates. Transfer of a non-transferable group?

Oxidative decomposition of cyanocuprates of the type CuLi(CN)Ar (Ar = [C6H4(CH2NMe2)-2]-, 1a) or type CuLi2(CN)Ar2(1b) shows the unexpected formation of aryl-cyanides in up to 30% yield.

Self-assembling of bis-ortho chelated diaminobenzyl- (NC′N) and butyl-lithium units to give 2:2 mixed alkyllithium aggregates (NC′N)Li2Bu2Li2(NC′N) with a ladder structure

The lithiation reaction of 1,3-bis(dimethylaminomethyl)-4,6-dimethyl-2-(trimethylsilylmethyl)benzene 2 with BunLi (2 equiv.) affords a unique aggregated species 3 of the parent lithiated compound and BunLi in a 2:2 ratio in which the bridging carbon atoms and the lithium atoms are arranged in an unprecedented ladder-type arrangement with exclusively bridging alkyl groups.